Method and apparatus for measuring air entrainment



Aug. 20,1946.

METHOD AND APPARATUS FOR MEASURING AIR ENTRAINMENT B. R. WALSH ETAL Filed Nov. 24, 1943 2 Sheets-Shet 1 ENGINE 72 I j 26 i 15 I 12 19 k 16 26 10 I P I a 27 6 '2l 25 15 f I INVENTORS I BRUCE R-WBLSH l GIB9RG,ES.PTRSON W14 ORNEY w msmwmwnm HHDAOWQK I WMIQE 2 Sheets-Sheet 2 B. R. WALSH ETAL Filed Nov. 24, 1943 METHOD AND APPARATUS FOR MEASURING AIR ENTRAINMENT urns as; 's rtcmnsscmci as-mwHosm INVENTOK Ruc: Rw L5H g1 GEOgfEFSfETERSON ATTORNEY 0 w 2 NH 3 Q 9 ON 3 3 on o I ofl ou g Zia an om I Kgi FZWQuON I 0Q] ow ow om l -t QPFEZDQ OZ OOHI Aug. 20, 1946.

Patented Aug. 20, 1946 p UNITED S ATE P FI CE ,METHOD AND APPARATUS FOR MEASURING AIR ENTRAINMENT Bruce R. Walsh, Wilkinsburg, and George S. Peterson, Penn Township, Allegheny County, Pa., assignors, by mesne assignments, to Wright Aeronautical Corporation, Paterson, N. J a corr poration of New York Application November 24, 1943, Serial No.'511,604

7 Claims. 73 53).

vThis invention relates to methods and ap- .A further object of the invention is to provide paratus for measuring air entrainment, useful a continuously operating indicator of the char-- for determining the presence and percentage of actor described which shall be smallin size and gas in liquid or semi-liquid materials, such for of. a few number of parts and which may be instance as lubricating oil, grease, plastic maportable or be a permanent part of almost any terial, oil well drilling mud and the like. More type of hydraulic installation, as for example particularly the invention is concerned with the lubricating system of an airplane engine,'a-

methods and apparatus for continuously indicathydraulic brake or power transmission system ing the percentage of gas at a point in a flowing or a system for handling liquidssuch as a liquid stream of such'liquid or semi-liquid material. fly feeding or measuring device. l a

In many modern hydraulic installations it is de- .A further object of t invention is the P sirable, if not imperative, to know of the presence vision of continuous indicating means of the charand percentage of gas in the liquid in the system. acter described which may be connected at al- 3 Thus, in some pressure lubricating systems the 6 most any po nt n a y a c System, such date presence of an excess of entrained air or gas in a reservoir 0r t0 a flowing Stream O l qu d, and

the lubricant may seriously impair its efiiciency. Wh ch W l not n e e W he n m p a- Mud used in drilling oil wells may sometimes betieh f the systemi come so laden with air or gas that disaster re- Ac d to the present invention use is made sults. Hydraulic systems for transmitting energy of a o y p sitive displacement p p D may operate erratically or fail completely if air zbvided with a fixed orifice discharge. .The .inbecomes mixed with the liquid us d, and liquid herent characteristics of such a device, when. feeding devices may fail to function or measure u p n iquids nta nin n a d a a accurately. such that when operated at constant speed the It is old in the art to which this invention discharge p e f e p mp f l 0 f r relates to determine the percentage of gas in liquid creases With increase in the p c a of a o or semi-liquid material by examination of ingas in e q WithafiXed erifieein the P p dividual samples of the material. One such meth- Outlet w h q s a d fin t d s ha p sodinvolves securing a measured volume of the Sure for each D p fl rate, e discharge D s material to be tested and subjecting it to pressure of the liquid D p d fa s O f With decreassure in a, closed container whereby itsvolume is 39 mg inlet absolute pr e, in a manner t be reduced. Another method consists in comparing described, because the flow falls off. Thus a still the weight 01 a wh of material of known further object of the invention is the provision of gaseous content with the weight of an equal volppa atus of the cha t ri d mbodyin ume of material of unknown gaseous content. Z Continuously pe positive d p m t However, such methods are discontinuous and ridadvan a usly a su ta t a y stant are limited for the most part to use in the lab- Speed rotary p D- oratory. These and other objects are accomplished by Apparatus involving the use of electric circuits the p n inv n n a Wil be pp nt from containing electrical condensers, resistances or the following d sc pti n and at mnanyin v light sensitive electric cells have been proposed 40 raw wherein,

for continuously indicating the percentage of gas Fig. 1 is a top p V p y in Section, f in liquids but these devices, while possibly sound e indicator of the p t invention; theoretically, are complicated and delicate and F 2 is a f n plan v w f t appara us have not proven entirely satisfactory under prac- OWn i tical conditions of operation. Fig. 3'is a diagrammatic view, partly in sec- It is an object of the present invention to protion. d ShOWS One m of apparatus of the vide an improved method for continuously indipresent invention connected to the lubricating eating the percentage of gas entrained in liquids. y m, Of an e; a d

A further object of the invention is to provide Fig. 4 is a chart in which indicator inlet and a strong and durable, inexpensive and simply con- Joutlet pressures are graphically illustrated by structed direct reading apparatus for continucurves for lubricating oil containing various perously and accurately indicating the presence or centages of air at different altitudes, as when the absence,-or change in percentage of gas in liquids, oil is used to lubricate an airplane engine. semi-liquida'plastic material, or liquids contain- Referring to the drawings and more particuing solids. I g 56 Ilarly to Figs. 1 and 2, wherein like numerals indled is indicated regardless of whether the gas be simply entrained or mechanically admixed with the material orliberated from solution in the liquid by the drop in pressure in the system. While the invention is particularly meritorious in airplane lubricating systems it is well adapted for Wide application in industry.

What is claimed is:

1. The method of continuously indicating the percentage of gas in a liquid-gas mixture which comprises preparing a calibration chart of a positive displacement pump driven at constant speed and discharging through a constant resistance, in which pump discharge pressures are plotted against pump inlet pressures for liquids containing various known percentages of entrained gas, thereby obtaining a series of characteristic curves, pumping a liquid containing an unknown percentage of entrained gas with said pump at said speed and through said resistance, determining the inlet and outlet pressures of the liquid and noting the percentage of entrained gas in the liquid represented on the chart by the curve having the nearest comparative corresponding pressure readings.

2. The subject matter of claim 1 wherein the inlet temperatures of the liquid-gas mixture used in preparing the calibration chart of the positive displacement pump and the liquid-gas mixture containing an unknown percentage of entrained gas are made equal.

3. The subject matter of claim 1 wherein a plurality of said charts are prepared corresponding to operations of the positive displacement pump with liquid-gas mixtures of different temperatures, determining the temperature of the unknown liquid-gas mixture and referring to the chart representing operation of the pump nearest the temperature of the unknown liquid-gas mixture for determining the percentage gas present in said liquid.

4. In combination with a system including a flowing stream of liquid containing entrained gas, a by-p-ass in said system, a positive displacement pump in said by-pass, means for determining the pressure of the liquid-gas mixture entering the pump, a fixed fluid flow resistance in the outlet of the pump, a pressure gage in the outlet of the pump intermediate the pump and the resistance and means for driving the pump at a substantially constant speed whereby a difference in pressure across. said pump is obtained, said difference being less the greater the percentage of gas present with the liquid.

5. In apparatus for measuring the quantity of gas entrained in a mixture of liquid and gaseous material, the improvement comprising a positive displacement pump, inlet and outlet connections for the pump, a pressure gage arranged to indicate the pressure of the liquid-gas mixture on the inlet side of the pump, a fixed orifice resistance in said pump outlet connection, a pressure gage connected to the pump outlet intermediate the pump and the orifice resistance, and means for driving the pump at a substantially constant speed whereby a difference in pressure across said pump is obtained, said difierence being less the greater the percentage of gas present with the liquid.

6. Apparatus for use with a calibration chart of -a positive-displacement pump operating at a given speed, said chart showing the relation between the pump inlet and outlet pressures when pumping liquid-gas mixtures of variousekno-wn percentages of gas through a fixed restricted orifice; said apparatus comprising a positive-displacement pump for which said chart is calibrated, means for operating said pump at said given speed, a fixed restricted orifice similar to the orifice upon which said chart is based, said pump being arranged to pump a liquid-gas mixture through said orifice, means for measuring the pump inlet pressure, and means for measuring the pump outlet pressure upstream of said orifice.

7. Apparatus for measuring the quantity of gas in a liquid-gas mixture, said apparatus comprising a positive-displacement pump, a restricted passage through which said pump is arranged to pump said mixture, means for operating said pump at a substantially constant speed, means for measuring the pump intake pressure, and

' means for measuring the pump discharge pressure upstream of said restricted orifice.

BRUCE R. WALSH. GEORGE S. PETERSON. 

